Sept. 15, 2011 -- Eating lots of white-fleshed fruit such as apples and pears may significantly reduce the risk of stroke.

In a new study, Dutch researchers set out to determine a possible link between stroke risk and eating fruits and vegetables of various colors. They took a look at self-reported information from 20,069 people between ages 20 and 65 of what they ate over a one-year period.

All of the people had no previous diagnosed heart disease or stroke at the start of the study.

During the 10 years of follow-up, 233 people had strokes. The researchers say the risk of stroke was 52% lower for people who ate a lot of white-fleshed fruits and vegetables, compared to those who didn't.

Every Little Bit Helps

The researchers found that each 25-gram daily increase of white fruits and vegetables was associated with a 9% lower risk of stroke. To put that in context, a single apple is about 120 grams.

"To prevent stroke, it may be useful to consume considerable amounts of white fruits and vegetables," Linda M. Oude Griep, MSc, of Wageningen University in the Netherlands, says in a news release.

She says an apple a day "is an easy way to increase white fruits and vegetable intake," but because other fruits and vegetable color groups also protect against chronic diseases, it's important to eat a lot of different fruits and vegetables.

Foods in the white category also include bananas, cauliflower, chicory, and cucumbers. Potatoes were classified as a starch.

Color Reflects Presence of Beneficial 'Phytochemicals'

The color of the edible portions of fruits and vegetables reflects the presence of beneficial phytochemicals (plant compounds), such as carotenoids and flavonoids.

In the study, researchers divided fruits and vegetables into four color groups: Green (dark leafy vegetables, cabbages, and lettuces), orange-yellow (mostly citrus fruits), red-purple (mostly red vegetables), and white, of which 55% were pears and apples.

Previous studies on protective effects of fruits and vegetables have focused on the food's nutritional value and characteristics, such as the edible part of the plant, the color, the botanical family, and its ability to provide antioxidants.

The researchers write that they believe their study is the first to examine fruit and vegetable color groups in relation to stroke.

Still, they say that more study is needed to confirm their findings. "It may be too early for physicians to advise patients to change their dietary habits based on these initial findings," Oude Griep says.

Current Guidelines for Fruits and Vegetables

Currently, the U.S. Preventive Health Services recommends that daily diets include vegetables from five subgroups: dark green, red-orange, legume, starchy, and other vegetables.

Heike Wersching, MD, MSc, of the University of Munster in Germany, writes in an accompanying editorial that even though the Dutch researchers' study group was "remarkably large," their results should be interpreted with caution.

First, Wersching says participants filled out questionnaires about what they ate, meaning it relied on their memory, which is not always a totally reliable method for gathering and interpreting data.

Also, Wersching writes that it's possible that the Dutch scientists' findings could be due to "a generally healthy lifestyle" of people who have diets rich in fruits and vegetables.

Wersching concludes, however, that if the findings of the Oude Griep group are replicated, "the time for an 'apple a day' clinical trial has come."

The study and editorial are published in Stroke: Journal of the American Heart Association.